Zero platinum group metal catalysts

ABSTRACT

The present invention relates improving the performance of nitrogen oxide reduction by exposing rich exhaust to catalysts systems comprising a catalyst, wherein the catalyst systems are free of platinum group metals. The present invention also relates to improving reduction of carbon monoxide and hydrocarbon in exhaust by introducing air into a portion of the exhaust between a first catalyst system and a second catalyst system. The present invention also relates to improving nitrogen oxide, carbon monoxide and hydrocarbon reduction by (1) exposing rich exhaust to a first catalysts system, wherein the exhaust has an R value of greater than 1.0 and the first catalyst system comprises a catalyst and is free of platinum group metals and (2) introducing air into a portion of the exhaust in between the first catalyst system and a second catalyst system, wherein the second catalyst system is free of platinum group metals.

RELATED APPLICATIONS

This application is a continuation-in-part application, which claims thebenefit of U.S. application Ser. No. 12/215,694 filed on Jun. 27, 2008,which is incorporated herein by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to improving the nitrogen oxide reductionin exhaust by exposing a rich exhaust to a catalyst which is free ofplatinum group metals. The present invention also relates to improvingreduction of carbon monoxide and hydrocarbon in exhaust by introducingair into a portion of the exhaust between a first catalyst system and asecond catalyst system. The present invention also relates to improvingnitrogen oxide, carbon monoxide and hydrocarbon reduction by (1)exposing rich exhaust to a first catalysts system, wherein the exhausthas an R value of greater than 1.0 and the first catalyst systemcomprises a catalyst and is free of platinum group metals and (2)introducing air into a portion of the exhaust in between the firstcatalyst system and a second catalyst system, wherein the secondcatalyst system is free of platinum group metals.

BACKGROUND OF THE INVENTION

Catalysts in catalytic converters have been used to decrease thepollution caused by exhaust from various sources, such as automobiles,utility plants, processing and manufacturing plants, airplanes, trains,all terrain vehicles, boats, mining equipment, and other engine-equippedmachines. A common catalyst used in this way is the three-way catalyst(“TWC”). The TWC works by converting carbon monoxide, hydrocarbons, andnitrogen oxides into less harmful compounds or pollutants. Specifically,a TWC works by simultaneously reducing the nitrogen oxides to nitrogenand oxygen, oxidizing carbon monoxide to less harmful carbon dioxide,and oxidizing unburnt hydrocarbons to carbon dioxide and water. Theprior art TWC is made using at least some platinum group metals.Platinum group metals are defined in this specification to meanplatinum, palladium, ruthenium, iridium, osmium, and rhodium in thisapplication unless otherwise stated.

With the ever stricter standards for acceptable emissions, the demand onplatinum group metals continues to increase due to their efficiency inremoving pollutants from exhaust. However, this demand along with otherdemands for platinum group metals places a strain on the supply ofplatinum group metals, which in turn drives up the cost of platinumgroup metals and therefore catalysts and catalytic converters.Therefore, there is a need for a catalyst that does not require platinumgroup metals, and has a similar or better efficiency as the prior artcatalysts.

Additionally, engines associated with TWC using platinum group metalsoperate at or near stoichiometric conditions. However, catalysts of thepresent invention show surprisingly significant improvement in nitrogenoxide reduction performance under rich operating conditions. Further,the present invention improves the reduction of carbon monoxide andhydrocarbon in exhaust by introducing air in between a first catalystsystem and a second catalyst system.

SUMMARY OF THE INVENTION

The present invention pertains to a method for reducing nitrogen oxideemission, comprising, exposing a rich exhaust to a catalyst, wherein therich exhaust has an R value of greater than 1.0, and wherein thecatalyst is free of platinum group metals. The catalyst may be a ZPGMtransition metal catalyst, a zeolite catalyst, or a mixed metal oxidecatalyst. According to an embodiment, the catalyst system is completelyfree of platinum group metals. In one embodiment, the rich exhaust isfrom an engine.

Another embodiment of the present invention pertains to a method forimproving carbon monoxide and hydrocarbon reduction in exhaust,comprising exposing the exhaust to a first catalyst system and exposingat least a portion of the exhaust to a second catalyst system in series;and introducing air into at least a portion (preferably withoutlimitation all) of the exhaust, wherein the first catalyst systemcomprises a first catalyst and is free of platinum group metals, whereinthe second catalyst system comprises a second catalyst and is free ofplatinum group metals; and wherein the air to fuel ratio is above about14.7 before the second catalyst system. In one embodiment, it ispossible for additional exhaust to be added after the first catalystsystem, and before air introduction. In another embodiment, it ispossible for additional exhaust to be added after air introduction. Inanother embodiment, a portion of the exhaust may bypass the secondcatalyst system, before or after the air introduction. In oneembodiment, the first catalyst and/or second catalyst may comprise aZPGM transition metal catalyst, a zeolite catalyst, or a mixed metaloxide catalyst.

The first and second catalyst system may be identical or different. Inanother embodiment, first and/or second the catalyst systems arecompletely free of platinum group metals. In another embodiment, thesecond catalyst system comprises at least one platinum group metal. Inanother embodiment, the air comprises oxygen in any amount.

Another embodiment of the present invention pertains to a method ofimproving the reduction of hydrocarbon, carbon monoxide, and nitrogenoxide in an exhaust comprising exposing the exhaust to a first catalystsystem, wherein the exhaust has an R value of greater than 1.0, andwherein the first catalyst system comprises a first catalyst and is freeof platinum group metals. Next, exposing a portion of the exhaust to asecond catalyst system, wherein the second catalyst system comprises asecond catalyst and is free of platinum group metals, and wherein thefirst catalyst system and the second catalyst system are in series.Finally, introducing air into the portion of the exhaust after the firstcatalyst system, wherein the portion of the exhaust has an air to fuelratio above about 14.7 after the air is introduced.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic of Architecture 1 for the catalyst systems ofthe present invention;

FIG. 2 shows a schematic of Architecture 2 for the catalyst systems ofthe present invention;

FIG. 3 shows a schematic of Architecture 3 for the catalyst systems ofthe present invention;

FIG. 4 shows the pore volume results for fresh catalyst systems ZPGM-1through ZPGM-5;

FIG. 5 shows the pore volume results for aged catalyst systems ZPGM-1through ZPGM-5;

FIG. 6 shows the surface area summary for fresh and aged catalystsystems ZPGM-1 through ZPGM-5;

FIG. 7 shows the x-ray diffraction analysis of a ZPGM-1 catalyst system(fresh and aged Ce_(0.6)La_(0.4)Mn_(0.6)Cu_(0.4)O_(x) powders);

FIG. 8 shows the x-ray diffraction analysis of a ZPGM-2 catalyst system(fresh and aged);

FIG. 9 shows the x-ray diffraction analysis of a ZPGM-3 catalyst system(fresh and aged);

FIG. 10 shows the x-ray diffraction analysis of a ZPGM-4 catalyst system(fresh and aged);

FIG. 11 shows the x-ray diffraction analysis of a ZPGM-5 catalyst system(fresh and aged);

FIG. 12 shows the x-ray diffraction analysis of a ZPGM-6 catalyst system(fresh and aged);

FIG. 13 shows the sweep test results for a ZPGM-1 catalyst system (freshand aged);

FIG. 14 shows the sweep test results for a ZPGM-2 catalyst system (freshand aged);

FIG. 15 shows the sweep test results for a ZPGM-3 catalyst system (freshand aged);

FIG. 16 shows the sweep test results for a ZPGM-4 catalyst system (freshand aged);

FIG. 17 shows the sweep test results for a ZPGM-5 catalyst system (freshand aged);

FIG. 18 shows the sweep test results for a ZPGM-6 catalyst system (freshand aged);

FIG. 19 shows the results of light off tests for an example of a Type DZPGM transition metal catalyst;

FIG. 20 shows the results of light off tests for an example of a TypeD/Type H ZPGM transition metal catalyst;

FIG. 21 shows the results of light off tests for an example of a TypeD/Type H ZPGM transition metal catalyst;

FIG. 22 shows the results of light off tests for an example of a Type Fmixed metal oxide catalyst;

FIG. 23 shows the results of light off tests for an example of a Type Fmixed metal oxide catalyst;

FIG. 24 shows the results of light off tests for an example of a Type Fmixed metal oxide catalyst;

FIG. 25 shows the results of light off tests for an example of a Type GZPGM transition metal catalyst;

FIG. 26 shows the results of light off tests for an example of a Type GZPGM transition metal catalyst;

FIG. 27 shows the results of light off tests for an example of a TypeG/Type D ZPGM transition metal catalyst;

FIG. 28 shows the results of light off tests for an example of a TypeG/Type D ZPGM transition metal catalyst;

FIG. 29 shows the results of ramp light off tests for an example of aType D ZPGM transition metal catalyst;

FIG. 30 shows the results of ramp light off tests for an example of aType I;

FIG. 31 shows light off test results for architecture 3;

FIG. 32 shows the results of a light-off test for a ZPGM-1 catalystsystem (fresh and aged);

FIG. 33 shows the results of a light-off test for a ZPGM-2 catalystsystem (fresh and aged);

FIG. 34 shows the results of a light-off test for a ZPGM-3 catalystsystem (fresh and aged);

FIG. 35 shows the results of a light-off test for a ZPGM-4 catalystsystem (fresh and aged);

FIG. 36 shows the results of a light-off test for a ZPGM-5 catalystsystem (fresh and aged); and

FIG. 37 shows the results of a light-off test for a ZPGM-6 catalystsystem (fresh and aged).

FIG. 38 shows a schematic of Design 1 for the catalyst systems of thepresent invention;

FIG. 39 shows the sweep test results for a ZPGM-1 catalyst system (freshand aged);

FIG. 40 shows the sweep test results for a ZPGM-2 catalyst system (freshand aged);

FIG. 41 shows the sweep test results for a ZPGM-3 catalyst system (freshand aged);

FIG. 42 shows the sweep test results for a ZPGM-4 catalyst system (freshand aged);

FIG. 43 shows the sweep test results for a ZPGM-5 catalyst system (freshand aged);

FIG. 44 shows the sweep test results for a ZPGM-6 catalyst system (freshand aged);

FIG. 45 shows the sweep test results for the fresh and aged Type Gcatalyst with a composition of 10% Cu/CuLa_(0.04)Al_(1.96)O₄;

FIG. 46 shows the sweep test results for the fresh and aged Type Dcatalyst with a composition of 12.4%CuO/Ce_(0.3)Zr_(0.6)Nd_(0.05)Pr_(0.05)O₂+Al₂O₃, 75:25;

FIG. 47 shows the sweep test results for the fresh and aged Type Dcatalyst with a composition of 16%CuO/Ce_(0.3)Zr_(0.6)Nd_(0.05)Pr_(0.05)O₂;

FIG. 48 shows the sweep test results for the fresh and aged Type Dcatalyst with a composition of 10% Cu+12% Ce/La—Al₂O₃; and

FIG. 49 shows the sweep test results for the fresh and aged Type Dcatalyst with a composition of 20% CuO/MgLa_(0.04)Al_(1.96)O₄.

DEFINITIONS

The following definitions are provided to clarify the invention.

The term “catalyst system” is defined in this specification to mean asubstrate, a washcoat, and optionally an overcoat as illustrated byArchitecture 1, Architecture 2, or Architecture 3 as set forth in FIGS.1, 2, and 3, respectively.

The term “substrate” is defined in this specification to mean anymaterial known in the art for supporting a catalyst and can be of anyshape or configuration that yields a sufficient surface area for thedeposit of the washcoat and/or overcoat, including, but not limited to ahoneycomb, pellets, or beads.

The term “washcoat” is defined in this specification to mean a coatingcomprising one or more oxide solids that is coupled with a substrate.

The term “overcoat” is defined in this specification to mean a coatingcomprising one or more oxide solids that is coupled with a substrate anda washcoat.

The term “oxide solid” is defined in this specification to mean one ormore selected from the group consisting of a carrier material oxide, acatalyst, and mixtures thereof.

The term “carrier material oxide” is defined in this specification tomean materials used for providing a surface for at least one catalystand comprises one or more selected from the group consisting of oxygenstorage material, aluminum oxide, doped aluminum oxide, spinel,delafossite, lyonsite, garnet, perovksite, pyrochlore, doped ceria,fluorite, zirconium oxide, doped zirconia, titanium oxide, tin oxide,silicon dioxide, zeolite, and mixtures thereof.

The term “oxygen storage material” is defined in this specification tomean materials that can take up oxygen from oxygen-rich feed streams andrelease oxygen to oxygen-deficient feed streams. The oxygen storagematerial comprises one or more oxides selected from the group consistingof cerium, zirconium, lanthanum, yttrium, lanthanides, actinides, andmixtures thereof.

The term “catalyst” is defined in this specification to mean a catalystfor decreasing the amount of nitrogen oxide, hydrocarbon, carbonmonoxide, and/or sulfur that is free of platinum group metals,preferably completely free of platinum group metals.

The term “ZPGM Transition Metal Catalyst” is defined in thisspecification to mean a catalyst comprising one or more transitionmetals.

The term “Mixed Metal Oxide Catalyst” is defined in this specificationto mean a catalyst comprising at least one transition metal and at leastone other metal.

The term “Zeolite Catalyst” is defined in this specification to mean acatalyst comprising at least one zeolite and at least one transitionmetal.

The term “transition metal” is defined in this specification to mean thetransition metals of the periodic table excluding the platinum groupmetals, which are scandium, titanium, vanadium, chromium, manganese,iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium,molybdenum, technetium, ruthenium, silver, cadmium, hafnium, tantalum,tungsten, rhenium, gold, mercury, rutherfordium, dubnium, seaborgium,bohrium, hassium, meitnerium, ununnilium, unununium, ununbium, andgallium.

The term “copper” is defined in this specification to mean copper,copper complexes, copper atoms, or any other copper compounds known inthe art.

The term “free” is defined in this specification to mean substantiallyfree or completely free.

The term “impregnation component” is defined in this specification tomean one or more components added to a washcoat and/or overcoat to yielda washcoat and/or overcoat comprising a catalyst. The impregnationcomponent comprises one or more selected from the group consisting of atransition metal, alkali and alkaline earth metal, cerium, lanthanum,yttrium, lanthanides, actinides, and mixtures thereof.

The term “depositing,” “deposited,” or “deposit(s)” is defined in thisspecification to include, without limitation, placing, adhering, curing,coating (such as vacuum coating), spraying, dipping, painting and anyknown process for coating a film on a substrate.

The term “treating,” “treated,” or “treatment” is defined in thisspecification to include, without limitation, precipitation, drying,firing, heating, evaporating, calcining, or mixtures thereof.

The term “platinum group metals” is defined in this specification tomean platinum, palladium, ruthenium, iridium, osmium, and rhodium.

The term “coupled with” is defined in this specification to mean thewashcoat and/or overcoat is in a relationship with the substrate or eachother, such that they may be directly in contact with each other; orthey may be associated with each other, but there may be something inbetween each of them, e.g. the overcoat may be coupled with a substrate,but a washcoat may be in between the substrate and the overcoat.

The term “R value” is defined in this specification to mean moles ofreductant divided by moles of oxidant.

The term “exhaust” is defined in this specification to mean thedischarge of gases, vapor, and fumes created by and released at the endof a process, comprising hydrocarbons, nitrogen oxide, and/or carbonmonoxide.

The term “air to fuel (A/F) ratio” is defined in this specification tomean the mass ratio of air to fuel present in exhaust.

The term “introduce” is defined in this specification to mean inject,insert, infuse, add, instill, or mixtures thereof.

The term “air” is defined in this specification to mean any gascomprising oxygen in any amount, including 100% oxygen or less.

The term “conversion” is defined in this specification to mean thechange from harmful compounds (such as, without limitation,hydrocarbons, carbon monoxide, sulfur, and nitrogen oxide) into lessharmful and/or harmless compounds (such as, without limitation, water,carbon dioxide, and nitrogen).

The term “reduction” is defined in this specification to mean a decreasein an amount; to lessen or diminish.

Examples of catalyst systems are denoted by “ZPGM” and a number, e.g.“ZPGM-1”. Examples of catalysts are denoted by “Type” and a letter, e.g.“Type A”.

All percentages discussed herein are weight percent unless otherwiseindicated. All ratios discussed herein are weight ratios unlessotherwise indicated.

DETAILED DESCRIPTION

The catalyst system of the present invention is free of platinum groupmetals; decreases the amount of at least one of carbon monoxide,nitrogen oxides, hydrocarbon, and sulfur emissions; and comprises one ormore catalysts.

Substrates

The substrate of the present invention may be, without limitation, arefractive material, a ceramic substrate, a honeycomb structure, ametallic substrate, a ceramic foam, a metallic foam, a reticulated foam,or suitable combinations, where the substrate has a plurality ofchannels and at least the required porosity. Porosity is substratedependent as is known in the art. Additionally, the number of channelsmay vary depending upon the substrate used as is known in the art. Thechannels found in a monolith substrate are described in more detailbelow. The type and shape of a suitable substrate would be apparent toone of ordinary skill in the art. Preferably, all of the substrates,either metallic or ceramic, offer a three-dimensional support structure.

In one embodiment, the substrate may be in the form of beads or pellets.The beads or pellets may be formed from, without limitation, alumina,silica alumina, silica, titania, mixtures thereof, or any suitablematerial. In another embodiment, the substrate may be, withoutlimitation, a honeycomb substrate. The honeycomb substrate may be aceramic honeycomb substrate or a metal honeycomb substrate. The ceramichoneycomb substrate may be formed from, for example without limitation,sillimanite, zirconia, petalite, spodumene (lithium aluminum silicate),magnesium silicates, mullite, alumina, cordierite (e.g. Mg₂A₁₄Si₅O₁₈),other alumino-silicate materials, silicon carbide, aluminum nitride, orcombinations thereof. Other ceramic substrates would be apparent to oneof ordinary skill in the art.

If the substrate is a metal honeycomb substrate, the metal may be,without limitation, a heat-resistant base metal alloy, particularly analloy in which iron is a substantial or major component. The surface ofthe metal substrate may be oxidized at elevated temperatures above about1000° C. to improve the corrosion resistance of the alloy by forming anoxide layer on the surface of the alloy. This oxide layer on the surfaceof the alloy may also enhance the adherence of a washcoat to the surfaceof the monolith substrate.

In one embodiment, the substrate may be a monolithic carrier having aplurality of fine, parallel flow passages extending through themonolith. The passages can be of any suitable cross-sectional shapeand/or size. The passages may be, for example without limitation,trapezoidal, rectangular, square, sinusoidal, hexagonal, oval, orcircular, although other shapes are also suitable. The monolith maycontain from about 9 to about 1200 or more gas inlet openings orpassages per square inch of cross section, although fewer passages maybe used.

The substrate can also be any suitable filter for particulates. Somesuitable forms of substrates may include, without limitation, wovenfilters, particularly woven ceramic fiber filters, wire meshes, diskfilters, ceramic honeycomb monoliths, ceramic or metallic foams, wallflow filters, and other suitable filters. Wall flow filters are similarto honeycomb substrates for automobile exhaust gas catalysts. They maydiffer from the honeycomb substrate that may be used to form normalautomobile exhaust gas catalysts in that the channels of the wall flowfilter may be alternately plugged at an inlet and an outlet so that theexhaust gas is forced to flow through the porous walls of the wall flowfilter while traveling from the inlet to the outlet of the wall flowfilter.

Washcoats

According to an embodiment, at least a portion of the catalyst of thepresent invention may be placed on the substrate in the form of awashcoat. The oxide solids in the washcoat may be one or more carriermaterial oxide, one or more catalyst, or a mixture of carrier materialoxide(s) and catalyst(s). Carrier material oxides are normally stable athigh temperatures (>1000° C.) and under a range of reducing andoxidizing conditions. A preferable oxygen storage material is a mixtureof ceria and zirconia; more preferably a mixture of (1) ceria, zirconia,and lanthanum or (2) ceria, zirconia, neodymium, and praseodymium.

According to an embodiment, if a catalyst of the present inventioncomprises at least one oxygen storage material, the catalyst maycomprise about 10 to about 90 weight percent oxygen storage material,preferably about 20 to about 80 weight percent, more preferably about 40to about 75 weight percent. The weight percent of the oxygen storagematerial is on the basis of the oxides.

Various amounts of any of the washcoats of the present invention may becoupled with a substrate, preferably an amount that covers most of, orall of, the surface area of a substrate. In an embodiment, about 80 g/Lto about 250 g/L of a washcoat may be coupled with a substrate.

In an embodiment, a washcoat may be formed on the substrate bysuspending the oxide solids in water to form an aqueous slurry anddepositing the aqueous slurry on the substrate as a washcoat.

Other components may optionally be added to the aqueous slurry. Othercomponents such as acid or base solutions or various salts or organiccompounds may be added to the aqueous slurry to adjust the rheology ofthe slurry and/or enhance binding of the washcoat to the substrate. Someexamples of compounds that can be used to adjust the rheology include,but are not limited to, ammonium hydroxide, aluminum hydroxide, aceticacid, citric acid, tetraethylammonium hydroxide, other tetralkylammoniumsalts, ammonium acetate, ammonium citrate, glycerol, commercial polymerssuch as polyethylene glycol, polyvinyl alcohol and other suitablepolymers.

The slurry may be placed on the substrate in any suitable manner. Forexample, without limitation, the substrate may be dipped into theslurry, or the slurry may be sprayed on the substrate. Other methods ofdepositing the slurry onto the substrate known to those skilled in theart may be used in alternative embodiments. If the substrate is amonolithic carrier with parallel flow passages, the washcoat may beformed on the walls of the passages. Gas flowing through the flowpassages can contact the washcoat on the walls of the passages as wellas materials that are supported on the washcoat.

It is believed that the oxygen storage material may improve the rheologyof the washcoat slurry. Such an improvement may be seen in processcontrol and/or manufacture of the catalyst system. The enhanced rheologyof the washcoat slurry that may be due to the presence of the oxygenstorage material may enhance the adhesion of the washcoat slurry to thesubstrate.

Catalyst System Architecture

The catalyst system of the present invention may have one of thefollowing three architectures. In one embodiment, a catalyst system maycomprise a substrate (1) and a washcoat (2), wherein the washcoatcomprises at least one catalyst. See FIG. 1 (Architecture 1). In anotherembodiment, a catalyst system may comprise a substrate (1), a washcoat(2), and an overcoat (3), wherein the washcoat (2) and overcoat (3) eachcomprise at least one catalyst. See FIG. 2 (Architecture 2). In anotherembodiment, a catalyst system may comprise a substrate (1), a washcoat(2), and an overcoat (3), wherein the overcoat (3) comprises at leastone catalyst, but the washcoat (2) is free of catalyst, preferablycompletely free. See FIG. 3 (Architecture 3). The washcoat (2) of thethird catalyst system architecture comprises a carrier material oxide ormixtures thereof. Other components known to one of ordinary skill in theart may be included.

The Architectures depicted in FIGS. 1-3 show how the layers are appliedin order, but the end product may not have the layers as depicted dueto, without limitation, the reactions that may occur between the layers.

In the event that a washcoat (2) or an overcoat (3) with a catalyst isrequired, the washcoat (2) may be deposited in three different ways.First, depositing all desired components in one step. Or second,depositing components without a catalyst, and then separately depositingat least one impregnation component and heating (this separate depositis also referred to as an impregnation step). The impregnation componentcomprises, without limitation, transition metals, alkali and alkalineearth metals, cerium, lanthanum, yttrium, lanthanides, actinides, ormixtures thereof. The impregnation step converts metal salts into metaloxides creating a washcoat (2) comprising a catalyst. Third, depositingall desired components at once, including metal salts and then heatingto convert the metals salts to metal oxides.

The overcoat (3) is typically applied after treating the washcoat (2),but treating is not required prior to application of the overcoat (3) inevery embodiment. Preferably, the overcoat (3) is applied after thewashcoat (2).

According to an embodiment, a catalyst system comprises a substrate (1)and one or more catalyst selected from the group consisting of a ZPGMtransition metal catalyst, a mixed metal oxide catalyst, and a zeolitecatalyst.

ZPGM Transition Metal Catalyst

According to an embodiment, a catalyst system of the present inventioncomprises a ZPGM transition metal catalyst. A ZPGM transition metalcatalyst comprises one or more transition metals. Preferably thetransition metal is copper, nickel, iron, manganese, silver, cobalt,tungsten, niobium, molybdenum, or chromium; more preferably copper,nickel, iron, or manganese; most preferably copper, nickel, or cobalt.

According to an embodiment, the ZPGM transition metal catalystoptionally comprises one or more of a carrier material oxide. Preferablythe catalyst comprises a perovskite, a spinel, a lyonsite, an oxygenstorage material, alumina, or mixtures thereof; more preferably aspinel, an oxygen storage material, alumina, or mixtures thereof; mostpreferably at least one spinel and at least one oxygen storage material,or alumina and at least one oxygen storage material.

If a catalyst of the present invention comprises at least one oxygenstorage material, the catalyst may comprise about 10 to about 90 weightpercent oxygen storage material, preferably about 20 to about 80 weightpercent, more preferably about 40 to about 75 weight percent. The weightpercent of the oxygen storage material is on the basis of the oxides.

With any of the catalyst systems described herein, the catalysts mayoptionally further comprise one or more of a transition metal, alkalineearth metal, ceria, and mixtures thereof. Preferably, the transitionmetal is iron, manganese, or mixtures thereof. Preferably, the alkalineearth metal is magnesium, barium, or mixtures thereof.

According to an embodiment, the catalyst, referred to as “Type H”,comprises at least one transition metal and at least one carriermaterial oxide. The transition metals may be a single transition metal,or a mixture of transition metals which includes, but is not limited to,chromium, manganese, iron, cobalt, nickel, copper, silver, niobium,molybdenum, and tungsten. The preferred transition metals are copper,nickel and cobalt. The total amount of the transition metal(s) arepresent in about 5% to about 50% by weight of the total catalyst weightand may be present in any ratio of transitional metals.

According to an embodiment, the catalyst, referred to as “Type D”,comprises copper and one or more carrier material oxides. Optionally,additional transition metals may be included. The copper may be appliedthrough impregnation as discussed herein. The copper in the catalyst maybe present in about 5% to about 50% by weight, preferably about 5% toabout 30%, more preferably about 15% by weight.

According to an embodiment, a catalyst system, referred to as “ZPGM-6”,comprises a substrate, a washcoat, and an overcoat. The substratecomprises cordierite. The washcoat comprises a spinel and at least oneoxygen storage material, preferably the oxygen storage material is amixture of cerium, zirconium, and lanthanum. The spinel in thisembodiment comprises magnesium aluminum oxides. Additionally, the oxygenstorage material and the spinel may be present in the washcoat in aratio of 40 to about 60 by weight. If an impregnation step is required,copper, cerium, zirconium, and lanthanum may be added and heated toconvert metal salts into metal oxides that create a washcoat comprisingthe catalyst. The overcoat comprises copper oxide, a spinel, and atleast one oxygen storage material, preferably the oxygen storagematerial comprises a mixture of cerium, zirconium, neodymium, andpraseodymium. The spinel in this embodiment comprises magnesium aluminumoxides. The spinel and oxygen storage material of the overcoat may bepresent in the overcoat in a ratio of about 60 to about 40. The copperin the overcoat is present in about 5% to about 50%, preferably about10% to about 16% by weight.

According to an embodiment, a catalyst system, referred to as “ZPGM-5”,comprises a substrate, a washcoat, and an overcoat. The substratecomprises cordierite. The washcoat comprises lanthanum-doped aluminumoxide and at least one oxygen storage material, preferably the oxygenstorage material comprises a mixture of cerium, zirconium, neodymium,and praseodymium. Additionally, the oxygen storage material and thelanthanum-doped aluminum oxide may be present in the washcoat in a ratioof about 40 to about 60. The optional impregnation components comprisecopper, cerium, zirconium, and lanthanum. The overcoat comprises copperoxide, lanthanum-stabilized aluminum oxide, and at least one oxygenstorage material, preferably the oxygen storage material comprises amixture of cerium, zirconium, neodymium, and praseodymium. The aluminumoxide and oxygen storage material of the overcoat may be present in theovercoat in a ratio of about 75 to about 25. The copper in the overcoatis present in about 5% to about 50%, preferably about 15% by weight.

According to an embodiment, a catalyst system, referred to as “ZPGM-4”,comprises a substrate, a washcoat, and an overcoat. The washcoatcomprises tin aluminum oxide and at least one oxygen storage material,preferably the oxygen storage material comprises a mixture of cerium,zirconium, neodymium, and praseodymium. The tin aluminum oxide and theoxygen storage material may be present in the washcoat in a ratio offrom about 25:75 to about 75:25, preferably in a ratio of about 60 toabout 40. The optional impregnation components comprise copper, cerium,zirconium, and lanthanum. The overcoat comprises aluminum, copper, andat least one oxygen storage material, preferably the oxygen storagematerial comprises a mixture of cerium, zirconium, and lanthanum. Thealuminum oxide and oxygen storage material may be present in theovercoat in a ratio of about 60 to about 40. According to an embodiment,there is about 5% to about 30% copper by weight in the overcoat,preferably about 10% to about 20%, more preferably about 12%.

According to an embodiment, a catalyst system, referred to as “ZPGM-3”,comprises a substrate and a washcoat. The washcoat comprises copper, tinaluminum oxide, and at least one oxygen storage material, preferably theoxygen storage material comprises a mixture of cerium, zirconium,neodymium, and praseodymium. The tin aluminum oxide and the oxygenstorage material may be present in the washcoat in a ratio of about 60to about 40. If an impregnation step is used, the impregnationcomponents comprise copper, cerium, zirconium, and lanthanum. Thecerium, zirconium, and lanthanum may be present in the washcoat in aratio of about 60 to about 30 to about 10. The washcoat may compriseadditional transition metals. According to an embodiment, there is about5% to about 30% copper by weight in the washcoat, preferably about 10%to about 20%, more preferably about 12%.

According to an embodiment, a catalyst system, referred to as “ZPGM-2”,comprises a substrate and a washcoat. The washcoat may comprise, withoutlimitation, copper, aluminum oxide, and at least one oxygen storagematerial, preferably the oxygen storage material is a mixture of cerium,zirconium, and lanthanum. The aluminum oxide and the oxygen storagematerial may be present in the washcoat in a ratio of about 60 to about40. The copper in the washcoat may be about 5% to about 20% copper byweight, preferably about 8%. The washcoat coat may optionally compriseadditional transitional metals and/or ceria.

According to an embodiment, a catalyst system, referred to as “ZPGM-1”,comprises a substrate and a washcoat. The washcoat comprises at leastone carrier material oxide and a perovskite; preferably the carriermaterial oxide comprises an oxygen storage material, more preferablycomprises one or more selected from the group consisting of cerium,zirconium, lanthanum, neodymium, praseodymium, and mixtures thereof; andthe perovskite preferably is a mixture of cerium, lanthanum, manganeseand copper, having the specific formulaCe_(0.6)La_(0.4)Mn_(0.6)Cu_(0.4)O₃.

According to an embodiment, the catalyst, referred to as “Type A”,comprises at least one transition metal, at least one alkaline earthmetal, cerium, and at least one carrier material oxide. The transitionmetal, alkaline earth metal and cerium are present in about 5% to about50% by weight in any ratio of the three components. Preferably, thealkaline earth metals comprise one or more selected from the groupconsisting of magnesium, calcium, barium, and strontium. The transitionmetals may be a single transition metal, or a mixture of transitionmetals which include, but is not limited to, chromium, manganese, iron,cobalt, nickel, copper, niobium, molybdenum, and tungsten.

According to an embodiment, the catalyst, referred to as “Type C”,comprises at least one transition metal, at least one alkaline earthmetal, and at least one carrier material oxide. The transition metal maybe a single transition metal, or a mixture of transition metals whichinclude, but is not limited to, chromium, manganese, iron, cobalt,nickel, copper, niobium, molybdenum, tungsten, and silver. The alkalineearth metal may be, but is not limited to, magnesium, calcium, barium orstrontium. The preferred transition metals are copper, nickel, andcobalt, while the preferred alkaline earth metals are barium andstrontium. The alkaline earth metal and the transition metal may bepresent in a molar ratio of about 1:10 to 1:1 and at about 2% to about50% weight of the catalyst.

According to an embodiment, the catalyst, referred to as “Type E”,comprises at least one transition metal and a perovskite having theformula ABO₃. The transition metal may be, but is not limited to,copper, nickel, cobalt, manganese, iron, chromium, niobium, molybdenum,tungsten, and silver. Preferably, the transition metals are copper,nickel, and/or cobalt. “A” comprises lanthanum, cerium, magnesium,calcium, barium, strontium, lanthanides, actinides, or a mixturethereof. “B” comprises iron, manganese, copper, nickel, cobalt, cerium,or mixtures thereof. The transition metal(s) is present in about 2% toabout 30% by weight.

According to one embodiment, the Type E catalyst comprises a perovskite(ABO₃), at least one transition metal, and at least one a carriermaterial oxide. The transition metal may be a single transition metal,or a mixture of transition metals which includes, but is not limited to,chromium, manganese, iron, cobalt, nickel, copper, niobium, molybdenum,tungsten, silver, or mixtures thereof. The perovskite and transitionmetal are present in about 5% to about 50% by weight.

According to an embodiment, the catalyst, referred to as “Type G”,comprises at least one transition metal and a spinel having the formulaAB₂O₄. The transition metal may be, but is not limited to, copper,nickel, cobalt, manganese, iron, chromium, niobium, molybdenum,tungsten, and silver. The preferred transition metals include, copper,nickel, and cobalt; more preferably copper. “A” and “B” each comprisealuminum, magnesium, manganese, gallium, nickel, copper, cobalt, iron,chromium, niobium, titanium, tin, or mixtures thereof. A preferredspinel is MgAl₂O₄. The transition metal(s) are present in about 2% toabout 30% by weight.

According to one embodiment, the Type G catalyst comprises a spinel(AB₂O₄), a transition metal, and a carrier material oxide. Thetransition metal may be a single transition metal, or a mixture oftransition metals which includes, but is not limited to, chromium,manganese, iron, cobalt, nickel, copper, niobium, molybdenum, tungsten,and/or silver. A preferred spinel is MgAl₂O₄. The spinel and transitionmetal(s) are present in about 5% to about 50% by weight.

Mixed Metal Oxide Catalyst

According to an embodiment, a catalyst may be a mixed metal oxidecatalyst, which comprises at least one transition metal and at least oneother metal. The other metals of the mixed metal oxide may include, butare not limited to alkali and alkaline earth metal, lanthanides, oractinides. For example, the mixed metal oxide may be a spinel, aperovskite, a delafossite, a lyonsite, a garnet, or a pyrochlore.

According to an embodiment, the catalyst, referred to as “Type B”,comprises a perovskite having the formula ABO₃ or a related structurewith the general formula A_(a-x)B_(x)MO_(b), wherein “a” is 1 or 2, “b”is 3 when “a” is 1 or “b” is 4 when “a” is 2, and “z” is a numberdefined by 0.1≦x<0.7. “A” comprises lanthanum, lanthanides, actinides,cerium, magnesium, calcium, barium, strontium, or mixtures thereof. “B”comprises a single transition metal, or a mixture of transition metalsincluding but not limited to iron, manganese, copper, nickel, cobalt,and cerium, or mixture thereof. According to an embodiment, the catalystmay have the formula AMn_(1-x)Cu_(x)O₃, wherein “A” is lanthanum,cerium, barium, strontium, a lanthanide, or an actinide and “x” is 0 to1.

According to another embodiment, the Type B catalyst may have theformula ACe_(1-x)Cu_(x)O₃, wherein “A” is barium, strontium, or calcium,and “x” is 0 to 1. According to an embodiment, about 10 g/L to about 180g/L of the formula ABO₃ may be coupled with the substrate.

According to one embodiment, the Type B catalyst comprises a perovskite(ABO₃) or related structure (with general formula A_(a-x)B_(x)MO_(b))and one or more of a carrier material oxide. The perovskite or relatedstructure is present in about 5% to about 50% by weight.

According to an embodiment, the catalyst, referred to as “Type F”,comprises a spinel having the formula AB₂O₄. “A” and “B” of the formulais aluminum, magnesium, manganese, gallium, nickel, copper, cobalt,iron, chromium, titanium, tin, or mixtures thereof.

According to an embodiment, the Type F catalyst comprises a spinel and acarrier material oxide. The spinel is present in about 5% to about 50%by weight.

Zeolite Catalyst

According to an embodiment, a catalyst may be a zeolite catalystcomprising a zeolite or mixture of zeolites and at least one transitionmetal. A zeolite is mixed aluminosillicates with regular interconnectedpores. The zeolite includes, but is not limited to ZSM5, heulandite,chabazite, or mixtures thereof, preferably ZSM5. According to anembodiment, the catalyst, referred to as “Type I” comprises at least onetransition metal impregnated into a zeolite or mixtures of zeolite. Thetransition metal(s) may be a single transition metal or a mixture oftransition metal which includes, but is not limited to, chromium,gallium, manganese, iron, cobalt, nickel, copper, niobium, molybdenum,tungsten, and silver. Preferably, the transition metals are selectedfrom the group consisting of copper, nickel, gallium, cobalt, andmixtures thereof. The transition metals may be present in about 3% toabout 25% by weight in any ratio of transition metals.

According to an embodiment, the catalysts of the present invention mayreduce pollutants emitted from exhaust. This is done by passing exhaustsubstantially through a catalyst system, such that the flowing exhaustreduces the pollutants. The exhaust includes, but is not limited toexhaust from an automobile, vehicle, factory, train, airplane, building,and laboratory. Pollutants are any compounds, substances, gases, orwaste that causes damage to water, air, land, and any other part of theenvironment, including carbon monoxide, hydrocarbons, nitrogen oxides,and sulfur.

The catalysts of the present invention to decrease the amount ofnitrogen oxide emissions. For example: NO+½O₂→NO₂ and6NO₂+8NH₃→7N₂+12H₂O. The catalyst also decreases the amount of theunburned hydrocarbons and carbon monoxide by oxidizing them. Forexample: 2C_(x)H_(y)+(2x+y/2)O₂→2xCO₂+yH₂O or 2CO+O₂→2CO₂. The catalystsmay also decrease the amount of sulfur emissions.

According to an embodiment, a catalyst system comprises a first catalystsystem and a second catalyst system. The first catalyst system may beany catalyst described herein. The second catalyst system comprises acatalyst comprising at least one platinum group metal, wherein thecatalyst may comprise any platinum group metal known in the art,including, but not limited to mixtures of platinum group metals andcarrier material oxides. The first catalyst system and the secondcatalyst system may be in an orientation such that a gas stream iscapable of passing through the first catalyst system followed by thesecond catalyst system in series or vice versa. Further, a catalystsystem may comprise more than a first and a second catalyst system, e.g.a third catalyst system.

Preparation of a Zero Platinum Group Metal Catalyst by Impregnation

A washcoat having the properties discussed herein may be prepared bymethods well known in the art. The washcoat may comprise any of thecatalysts and/or additional components described herein. The washcoat isdeposited on a substrate and is treated. The treating is done at atemperature between 300° C. and 700° C., preferably about 550° C. Thetreating may last from about 2 to about 6 hours, preferably about 4hours. After the washcoat and the substrate are treated, they are cooledto about room temperature. After the washcoat and the substrate arecooled, the washcoat is impregnated with at least one impregnationcomponent. The impregnation component includes, without limitation, atransition-metal salt or salts being dissolved in water and impregnatedon the washcoat. Following the impregnation step, the washcoat with theimpregnation components are treated. The treating may be performed atabout 300° C. to about 700° C., preferably about 550° C. The treatingmay last from about 2 to about 6 hours, preferably about 4 hours.

According to an embodiment, the substrate, the washcoat, and theimpregnation components may be treated to form the catalyst compositionbefore or after the washcoat and/or the impregnation components areadded to the substrate. In an embodiment, the washcoat and theimpregnation component may be treated before coating.

The impregnation method may be performed on an overcoat. Afterdepositing the overcoat, the overcoat is impregnated with at least oneimpregnation component. The impregnation component includes, withoutlimitation, a transition-metal salt or salts being dissolved in waterand impregnated on the overcoat. Following the impregnation step, theovercoat with the impregnation components are treated. The treating maybe performed at about 300° C. to about 700° C., preferably about 550° C.The treating may last from about 2 hours to about 6 hours, preferablyabout 4 hours.

Preparation of a Zero Platinum Group Metal Catalyst by Precipitation

The method of precipitation includes precipitating a transition metalsalt or salts on a washcoat. The transition metal salt or salts may beprecipitated with, but is not limited to NH₄OH, (NH₄)₂CO₃,tetraethylammonium hydroxide, other tetralkylammonium salts, ammoniumacetate, or ammonium citrate. The washcoat may be any washcoat describedherein. Next, the precipitated transition metal salt or salts andwashcoat are treated. The treating may be from about 2 hours to about 24hours. Next, the precipitated transition metal salt or salts and thewashcoat are deposited on a substrate followed by treating for about 2hours to about 6 hours, preferably about 4 hours at a temperature ofabout 300° C. to about 700° C., preferably about 550° C. Optionally,after treating, an overcoat may be deposited on the treated precipitatedtransition metal salt or salts and washcoat and treated again. Theovercoat may be treated for about 2 hours to about 6 hours, preferablyabout 4 hours and at a temperature of about 300° C. to about 700° C.,preferably about 550° C.

Preparation of a Zero Platinum Group Metal Catalyst by Co-Milling

A catalyst and a carrier material oxide are milled together. Thecatalyst can be synthesized by any chemical technique such as, but notlimited to solid-state synthesis, precipitation, or any other techniqueknown in the art. The milled catalyst and carrier material oxide aredeposited on a substrate in the form of a washcoat and then treated. Thetreatment may be from about 2 hours to about 6 hours, preferably about 4hours and at a temperature of about 300° C. to about 700° C., preferablyabout 550° C. Optionally, an overcoat may be deposited on the treatedcatalyst after cooling to about room temperature. The overcoat, washcoatand substrate are treated for about 2 hours to about 6 hours, preferablyabout 4 hours and at a temperature of 300° C. to about 700° C.,preferably about 550° C.

Improved Nitrogen Oxide Reduction Under Rich Conditions

According to an embodiment, exposing a rich exhaust to a catalyst systemas described herein significantly improves nitrogen oxide reductionperformance. It is expected that a catalyst comprising platinum groupmetals will show a small improvement in nitrogen oxide reductionperformance as the exhaust stream becomes richer. However, an unexpectedimprovement in nitrogen oxide reduction performance was observed forcatalyst systems having substantially no platinum group metals asdescribed herein under fuel-rich conditions.

Exhaust may be from any source in which exhaust is created, includingbut not limited to, an engine, burner, boiler, and utility plant.Fuel-rich conditions include exhaust having an R value of greater than1.0, preferably greater than 1.1.

In an embodiment, the catalyst system is free of platinum group metals,preferably completely free of platinum group metals.

Injection of Air Between Catalysts Systems Improves Carbon Monoxide andHydrocarbon Reduction

According to an embodiment, reduction of carbon monoxide and hydrocarbonin exhaust can be improved by increasing the air to fuel (A/F) ratio inan exhaust by introducing air into at least a portion of the exhaustflowing between a first catalyst system and a second catalyst system.See FIG. 38. In an embodiment, the air to fuel ratio is increased toabout 14.7 or greater. In an embodiment, the first catalyst systemand/or the second catalyst systems are free of platinum group metals,preferably completely free of platinum group metals.

The catalyst system is designed so that air is introduced (preferablyinjected) into at least a portion (preferably all) of the exhaustbetween the first catalyst system and the second catalyst system tolower the R-value (increase the A/F ratio). See FIG. 38. In oneembodiment, it is possible for additional exhaust to be added after thefirst catalyst system, and before air introduction. In anotherembodiment, it is possible for additional exhaust to be added after airintroduction. In another embodiment, a portion of the exhaust may bypassthe second catalyst system, before or after the air introduction. Theadditional air increases the amount of oxygen available and therebyimproves the carbon monoxide and hydrocarbon oxidation reduction of thecatalyst system. The air comprises oxygen in any amount.

The first catalyst system and the second catalyst system can be anydescribed herein. Further, the second catalyst system may compriseplatinum group metals.

In some embodiments, more than two catalyst systems can be used, whereinair is introduced in between the first and second catalyst system,between the second and third catalyst system, or between any twocatalyst systems (and may be introduced in between multiple catalystsystem pairs).

According to an embodiment, reduction of hydrocarbon, carbon monoxide,and nitrogen oxide in exhaust may also be improved by combining (1)exposing a first catalyst system comprising a catalyst that is free ofplatinum group metals to exhaust having rich conditions, and (2)introducing air into at least a portion of the exhaust between the firstcatalyst system and a second catalyst system to increase the A/F ratioto about 14.7 or greater, wherein the second catalyst system comprises acatalyst that is free of platinum group metals.

The following examples are intended to illustrate, but not to limit, thescope of the invention. It is to be understood that other proceduresknown to those skilled in the art may alternatively be used.

EXAMPLE 1 Pore Volume and Surface Area Measurements for Zero PlatinumGroup Metal Catalysts

FIG. 4 shows the measured pore volume for the fresh catalyst systemsZPGM-1 through ZPGM-5 and FIG. 5 shows the measured pore volume for theaged catalyst systems ZPGM-1 through ZPGM-5. The aged catalyst systemswere aged at 950° C. for 16 hours with 10% H₂O and air. The y-axis onthe right side of FIG. 4 is for the pore volume (cm³/g) of ZPGM-1 only.

The pore volumes were measured using a Micromeritics® (Norcross, Ga.)TriStar 3000 gas adsorption analyzer at 77K. The pore volumes wereobtained from the nitrogen adsorption isotherms using theBarrett-Joiner-Halenda (BJH) method (E. P. Barrett, L. G. Joyner, P. P.Halenda, “The determination of pore volume and area distributions inporous substances. I. Computations from nitrogen isotherms,” J. Am.Chem. Soc. (1951), 73, 373-380).

The results in FIGS. 4 and 5 show that the pore volume decreases for allthe catalyst systems (ZPGM-1 through ZPGM-5) upon aging. The averagepore volume for the fresh ZPGM-1 decreases from 0.106 cm³/g to 0.017cm³/g for the aged catalyst. Similarly, the average pore volume for thefresh ZPGM-2 decreases from 0.173 cm³/g to 0.116 cm³/g for the agedcatalyst. Again, the average pore volume for the fresh ZPGM-3 decreasesfrom 0.107 cm³/g to 0.010 cm³/g for the aged catalyst. The average porevolume for the fresh ZPGM-4 decreases from 0.190 cm³/g to 0.142 cm³/gfor the aged catalyst. The average pore volume for the fresh ZPGM-5decreases from 0.213 cm³/g to 0.122 cm³/g for the aged catalyst.

EXAMPLE 2 Surface Area Analysis for Fresh and Aged Catalyst SystemsZPGM-1 through ZPGM-5

The surface areas for the fresh and aged ZPGM catalyst systems arepresented in FIG. 6. The aged catalyst systems were aged at 950° C. for16 hours with 10% H₂O and air.

The surface areas were measured using a Micromeritics® (Norcross, Ga.)TriStar 3000 gas adsorption analyzer at 77K. The surface areas werecalculated using the BET (Brunauer, Emmitt and Teller) method (S.Brunauer, P. H. Emmett and E. Teller, J. Am. Chem. Soc., 1938, 60, 309).

The results in FIG. 6 show that the surface area decreases for allcatalyst systems (ZPGM-1 through ZPGM-5) upon aging. The surface areadecreases from 18.72 m²/g for the fresh ZPGM-1 to 2.76 m²/g for the agedcatalyst. Similarly, the surface area decreases from 38.60 m²/g for thefresh ZPGM-2 to 15.48 m²/g for the aged catalyst. The surface areadecreases from 30.78 m²/g for the fresh ZPGM-3 to 16.71 m²/g for theaged catalyst. The surface area decreases from 46.95 m²/g for the freshZPGM-4 to 22.06 m²/g for the aged catalyst. The surface area decreasesfrom 53.45 m²/g for the fresh ZPGM-5 to 24.02 m²/g for the agedcatalyst.

EXAMPLE 3 X-ray Diffraction Analysis for ZPGM Transition Metal Catalysts

FIG. 7-12 show the X-ray diffraction (XRD) patterns of fresh and agedcatalyst systems ZPGM-1 through ZPGM-6; the aged catalyst systems wereaged at 950° C. for 16 hrs with 10% H₂O and air.

The XRD analysis was conducted to determine the crystalline phasespresent for each catalyst system. The XRD patterns were measured on aRigaku® powder diffractometer (MiniFlex™) using Cu Kα radiation in the2-theta range of 20-70° with a step size of 0.050 and a dwell time of 2s. The tube voltage and current were set at 40 kV and 30 mA,respectively. The resulting diffraction patterns were analyzed using theInternational Centre for Diffraction Data (ICDD) database.

FIG. 7 shows the XRD spectra of the fresh and aged ZPGM-1 catalystsystem, Ce_(0.6)La_(0.4)Mn_(0.6)Cu_(0.4)O₃, shows the presence of theperovskite (open circles) and fluorite (filled squares) structures. Thefluorite and the perovskite structures are larger in the aged sample asevidenced by the sharper peaks.

FIG. 8 shows the XRD patterns of fresh and aged ZPGM-2 catalyst system,8% Cu impregnated on Al₂O₃+Ce_(0.64)Zr_(0.21)La_(0.15)O₂ (60:40 weightratio of Al₂O₃ to Ce_(0.64)Zr_(0.21)La_(0.15)O₂) (160 g/ml). The XRDspectrum of the fresh ZPGM-2 catalyst system shows the presence of thefluorite structure (open squares), alumina (A) and CuO (filled circles).The aged ZPGM-2 catalyst system shows fluorite (open squares), CuAl₂O₄(filled diamonds) and alumina (A). The fluorite structure is larger inthe aged sample as evidenced by the sharper peaks.

FIG. 9 shows the XRD patterns of fresh and aged ZPGM-3 catalyst system,8% Cu+6.1% Ce+2.4% Zr+1.5% La impregnated on 15%Sn—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (60:40 weight ratio ofSn—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂) (200 g/L). The XRDspectrum of the fresh ZPGM-3 catalyst system shows the presence of thefluorite structure (open circles), ZrO₂ (open squares), alumina (A) andCuO (filled circles). The aged ZPGM-3 catalyst system shows fluorite(open circles), ZrO₂ (open squares), SnO₂ (filled circles), CuAl₂O₄(filled diamonds) and alumina (A). The cordierite peak in the agedsample is from the substrate. During the aging the tin oxide dissociatesfrom the alumina, the Cu reacts with the Al₂O₃ to form CuAl₂O₄.

FIG. 10 shows the XRD patterns of fresh and aged ZPGM-4 catalyst system,which is composed of an overcoat containing 12% Cu impregnated onCe_(0.6)Zr_(0.21)La_(0.15)O₂+Al₂O₃ (60:40 weight ratio ofCe_(0.6)Zr_(0.21)La_(0.15)O₂ to Al₂O₃) and a washcoat containing 8%Cu+6.1% Ce+2.4% Zr+1.5% La impregnated impregnated on 15%Sn—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (60:40 weight ratio ofSn—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂). The XRD spectrum ofthe fresh ZPGM-4 catalyst system shows the presence of the fluoritestructure (filled circles), CeO₂ (open squares), alumina (A) and CuO(filled squares). The aged ZPGM-4 catalyst system shows fluorite (filledcircles), CeO₂ (open squares), SnO₂ (open circles), CuAl₂O₄ (filleddiamonds) and alumina (A). During the aging the tin oxide dissociatesfrom the alumina, the Cu reacts with the Al₂O₃ to form CuAl₂O₄.

FIG. 11 shows the XRD patterns of fresh and aged ZPGM-5 catalyst system,which is composed of an overcoat containing 12.4% CuO impregnated onLa—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (25:75 weight ratio ofLa—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂)(65 g/L) and a washcoatcontaining 8% Cu+6.1% Ce+2.4% Zr+1.5% La impregnated onLa—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (60:40 weight ratio ofLa—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂) (180 g/L). The XRDspectrum of the fresh ZPGM-5 catalyst system shows the presence of thefluorite structure (filled circles) and alumina (A). The aged ZPGM-5catalyst system shows fluorite (filled circles), CuAl₂O₄ (filleddiamonds) and alumina (A). During the aging the Cu reacts with the Al₂O₃to form CuAl₂O₄.

FIG. 12 shows the XRD patterns of fresh and aged ZPGM-6 catalyst system,which is composed of an overcoat containing 10% Cu+12% Ce impregnated onMgAl₂O₄+16% Cu impregnated on Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂(60:40 weight ratio of Ce impregnated on MgAl₂O₄ to 16% Cu impregnatedon Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂) (65 g/L) and a washcoatcontaining 4% Cu+6.1% Ce+2.4% Zr+1.5% La impregnated onMgAl₂O₄+Ce_(0.64)Zr_(0.21)La_(0.15)O₂ (60:40 weight ratio of MgAl₂O₄ toCe_(0.64)Zr_(0.21)La_(0.15)O₂) (180 g/L). The XRD spectrum of the freshZPGM-6 catalyst system shows the presence of two fluorite structures(filled and open circles), and MgAl₂O₄ (open diamonds). The aged ZPGM-6catalyst system shows two fluorite structures (filled and open circles),MgAl₂O₄ (open diamonds), CuAl₂O₄ (filled diamonds), and CuO (filledsquares). During the aging the CZL and CuO became more crystalline, andsome CuAl₂O₄ formed.

EXAMPLE 4 Sweep Test for Catalyst Systems ZPGM-1 Through ZPGM-6

FIGS. 13-18 show the sweep test results for catalyst systems ZPGM-1through ZPGM-6 (as described above in Examples 3-8), respectively. Thesweep test was performed with an inlet temperature of 600° C., anair/fuel span of ±0.2 and a cycle frequency of 1 Hz. A sweep testindicates the catalyst performance at various R-values (moles ofreductant divided by moles of oxidant). High conversions over a largerange of R-values indicate a promising catalyst because it can performwell under rich (R-values >1) and lean (R-values <1) engine conditions.The aged catalyst systems were aged at 1050° C. for 10 hrs cyclingbetween a 56 second rich segment and a 4 second lean segment.

FIG. 13 shows the sweep test results for the fresh and aged ZPGM-1catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >1.05, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with R-value >0.85. The catalytic properties for CO,hydrocarbons and NO decrease after aging; the NO conversion is <5% overthe entire R-value range tested. The CO conversion of the aged ZPGM-1decreases with increasing R-value. The HC conversion for the aged ZPGM-1is best for R-values between 0.95 and 1.05.

FIG. 14 shows the sweep test results for the fresh and aged ZPGM-2catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >1.05, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with R-value >0.85. The catalytic properties for CO,hydrocarbons and NO decrease after aging. The CO and HC conversions ofthe aged ZPGM-2 decrease with increasing R-value. The NO conversion isthe highest at R=0.85, for the aged ZPGM-2 catalyst system.

FIG. 15 shows the sweep test results for the fresh and aged ZPGM-3catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >1.05, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The catalytic properties for CO,hydrocarbons and NO decrease after aging. The CO and HC conversions ofthe aged ZPGM-3 decrease with increasing R-value. The NO conversion forthe aged ZPGM-3 increases with R-values >0.95.

FIG. 16 shows the sweep test results for the fresh and aged ZPGM-4catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >0.975, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The catalytic properties for CO,hydrocarbons and NO decrease after aging. The CO and HC conversions ofthe aged ZPGM-4 decrease with increasing R-value. The NO conversion forthe aged ZPGM-4 increases with R-values >0.95.

FIG. 17 shows the sweep test results for the fresh and aged ZPGM-5catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >0.975, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The catalytic properties for CO,hydrocarbons and NO decrease after aging. The CO and HC conversions ofthe aged ZPGM-5 decrease with increasing R-value. The NO conversion forthe aged ZPGM-5 increases with R-values >1.05.

FIG. 18 shows the sweep test results for the fresh and aged ZPGM-6catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >0.975, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The catalytic properties for CO,hydrocarbons and NO decrease after aging. The CO and HC conversions ofthe aged ZPGM-6 decrease with increasing R-value. The NO conversion forthe aged ZPGM-6 increases with R-values >0.975.

EXAMPLE 5 Light-Off Test for Type D or Type H ZPGM Transition MetalCatalysts

FIGS. 19-21 show the light-off test results for examples of Type D orType H ZPGM Transition Metal Catalysts. It should be noted that acatalyst may fall into one or more types, such as here, where thecatalyst is both Type D and Type H. A light-off test was performed onaged (800° C. for 16 hours, composed of a 56 second rich segment and a 4second lean segment) catalysts of the present invention. The test wasperformed by increasing the temperature from about 100° C. to 640° C. atR-value=1.05 and R-value=1.5. The light-off test measures theconversions of nitrogen oxide, carbon monoxide, and hydrocarbons as afunction of the catalyst system temperature. For a specific temperature,a higher conversion signifies a more efficient catalyst. Conversely, fora specific conversion, a lower temperature signifies a more efficientcatalyst.

FIG. 19 shows the results for Type D/H catalyst with a composition of16% Cu/Ce_(0.3)Zr_(0.6)Nd_(0.05)Pr_(0.05)O₂. It should be noted that acatalyst may fall into one or more types, such as here, where thecatalyst is both Type D and Type H. The light-off test at R=1.05 showsthat the catalyst has T₅₀ for CO at 267° C. and a T₅₀ for HC at 525° C.The maximum conversion for NO is about 2% at 640° C. Increasing theR-value to 1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀s for CO and HC decrease to 323° C. and 595° C., respectively. The NOlight-off at R=1.5 shows a T₅₀ of 494° C.

FIG. 20 shows the results for Type D/H catalyst with a composition of12% Cu/Ce_(0.6)Zr_(0.3)La_(0.1)O₂. It should be noted that a catalystmay fall into one or more types, such as here, where the catalyst isboth Type D and Type H. The light-off test at R=1.05 shows that thecatalyst has T₅₀ for CO at 237° C. and a T₅₀ for HC at 543° C. Themaximum conversion for NO is about 4% at 640° C. Increasing the R-valueto 1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀s for CO and HC decrease to 329° C. and 611° C., respectively. The NOlight-off at R=1.5 shows a T₅₀ of 515° C.

FIG. 21 shows the results for Type D/H catalyst with a composition of10% Cu+12% Ce/La—Al₂O₃. It should be noted that a catalyst may fall intoone or more types, such as here, where the catalyst is both Type D andType H. The light-off test at R=1.05 shows that the catalyst has T₅₀ forCO at 298° C. and a T₅₀ for HC at 546° C. The maximum conversion for NOis about 3% at 640° C. Increasing the R-value to 1.5 improves the NOconversion, but the CO and HC performance deteriorates. The light-offtest at R=1.5 shows that the catalyst has T₅₀s for CO and HC decrease to325° C. and 598° C., respectively. The NO light-off at R=1.5 shows a T₅₀of 461° C.

EXAMPLE 6 Light-Off Test for Type F ZPGM Transition Metal Catalysts

FIGS. 22-24 show the light-off test results for examples of Type Fcatalyst. A light-off test was performed on aged (800° C. for 16 hours,composed of a 56 second rich segment and a 4 second lean segment)catalysts of the present invention. The test was performed by increasingthe temperature from about 100° C. to 640° C, at R-value=1.05 andR-value=1.5. The light-off test measures the conversions of nitrogenoxide, carbon monoxide, and hydrocarbons as a function of the catalystsystem temperature. For a specific temperature, a higher conversionsignifies a more efficient catalyst. Conversely, for a specificconversion, a lower temperature signifies a more efficient catalyst.

FIG. 22 shows the results for Type F catalyst with a composition ofCuLa_(0.04)Al_(1.96)O₄. The light-off test at R=1.05 shows that thecatalyst has T₅₀ for CO at 334° C. The maximum conversions for NO and HCat 640° C. are about 6% and 38%, respectively. Increasing the R-value to1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀ for CO decreases to about 453° C. The NO light-off at R=1.5 shows aT₅₀ of 521° C. While, the maximum conversion for HC is about 16% at 640°C.

FIG. 23 shows the results for Type F catalyst with a composition ofCu_(0.5)Fe_(0.05)La_(0.04)Al_(1.96)O₄. The light-off test at R=1.05shows that the catalyst has T₅₀ CO at 346° C. and a T₅₀ for HC at 535°C. The maximum NO conversion is about 1% at 640° C. Increasing theR-value to 1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀s for CO and HC decrease to 368° C. and 588° C., respectively. The NOlight-off at R=1.5 shows a T₅₀ of 491° C.

FIG. 24 shows the results for Type F catalyst with a composition ofCuLa_(0.04)Al_(1.47)MnO_(0.49)O₄. The light-off test at R=1.05 showsthat the catalyst has T₅₀ for CO at 371° C. The maximum conversions forNO and HC at 640° C. are about 2% and 27%, respectively. Increasing theR-value to 1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀ for CO decreases to about 479° C. While, the maximum conversions forNO and HC are each about 16% at 640° C.

EXAMPLE 7 Light-Off Test for Type G ZPGM Transition Metal Catalysts

FIGS. 25-28 show the light-off test results for examples of Type G/TypeD catalyst. It should be noted that a catalyst may fall into one or moretypes, such as here, where the catalyst is both Type G and Type D. Alight-off test was performed on aged (800° C. for 16 hours, composed ofa 56 second rich segment and a 4 second lean segment) catalysts of thepresent invention. The test was performed by increasing the temperaturefrom about 100° C. to 640° C. at R-value=1.05 and R-value=1.5. Thelight-off test measures the conversions of nitrogen oxide, carbonmonoxide, and hydrocarbons as a function of the catalyst systemtemperature. For a specific temperature, a higher conversion signifies amore efficient catalyst. Conversely, for a specific conversion, a lowertemperature signifies a more efficient catalyst.

FIG. 25 shows the results for Type G/Type D catalyst with a compositionof 10% Ag/Cu_(0.5)Fe_(0.5)La_(0.04)Al_(1.96)O₄. It should be noted thata catalyst may fall into one or more types, such as here, where thecatalyst is both Type G and Type D. The light-off test at R=1.05 showsthat the catalyst has T₅₀ for CO at 383° C. The maximum conversions forNO and HC at 640° C. are about 1% and 33%, respectively. Increasing theR-value to 1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀ for CO decreases to about 394° C. The NO light-off at R=1.5 shows aT₅₀ of 485° C. While, the maximum conversion for HC is about 16% at 640°C.

FIG. 26 shows the results for Type G/Type D catalyst with a compositionof 10% Cu/CuLa_(0.04)Al_(1.96)O₄. It should be noted that a catalyst mayfall into one or more types, such as here, where the catalyst is bothType G and Type D. The light-off test at R=1.05 shows that the catalysthas T₅₀ for CO at 272° C. and a T₅₀ for HC at 464° C. There is nomeasured NO conversion up to 640° C. Increasing the R-value to 1.5improves the NO conversion, but the CO and HC performance deteriorates.The light-off test at R=1.5 shows that the catalyst has T₅₀s for CO andHC decrease to 375° C. and 565° C., respectively. The NO light-off atR=1.5 shows a T₅₀ of 500° C.

FIG. 27 shows the results for Type G/Type D catalyst with a compositionof 20% CuO/MgLa_(0.04)A_(1.96)O₄. It should be noted that a catalyst mayfall into one or more types, such as here, where the catalyst is bothType G and Type D. The light-off test at R=1.05 shows that the catalysthas T₅₀ for CO at 305° C. and a T₅₀ for HC at 513° C. The maximum NOconversion is about 1% at 640° C. Increasing the R-value to 1.5 improvesthe NO conversion, but the CO and HC performance deteriorates. Thelight-off test at R=1.5 shows that the catalyst has T₅₀s for CO and HCdecrease to 412° C. and 587° C., respectively. The NO light-off at R=1.5shows a T₅₀ of 478° C.

FIG. 28 shows the results for Type G/Type D catalyst with a compositionof 10% Cu+12% Ce/MgLa_(0.04)Al_(1.96)O₄. It should be noted that acatalyst may fall into one or more types, such as here, where thecatalyst is both Type G and Type D. The light-off test at R=1.05 showsthat the catalyst has T₅₀ for CO at 302° C. and a T₅₀ for HC at 506° C.The maximum NO conversion is about 2% at 640° C. Increasing the R-valueto 1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀s for CO and HC decrease to 338° C and 585° C., respectively. The NOlight-off at R=1.5 shows a T₅₀ of 461° C.

EXAMPLE 8 Light-Off Test for Type D ZPGM Transition Metal Catalysts

FIG. 29 shows the light-off test results for an example of Type Dcatalyst. A light-off test was performed on aged (800° C. for 16 hours,composed of a 56 second rich segment and a 4 second lean segment)catalysts of the present invention. The test was performed by increasingthe temperature from about 100° C. to 640° C. at R-value=1.05 andR-value=1.5. The light-off test measures the conversions of nitrogenoxide, carbon monoxide, and hydrocarbons as a function of the catalystsystem temperature. For a specific temperature, a higher conversionsignifies a more efficient catalyst. Conversely, for a specificconversion, a lower temperature signifies a more efficient catalyst.

FIG. 29 shows the results for Type D catalyst with a composition of 12%CuO/(Ce_(0.6)Zr_(0.3)La_(0.1)O₂+MgLa_(0.04)Al_(1.96)O₄ (40:60)). Thelight-off test at R=1.05 shows t the catalyst has T₅₀s for CO at 258°C., for HC at 381° C., and for NO at 519° C. Increasing the R-value to1.5 improves the NO conversion, but the CO and HC performancedeteriorates. The light-off test at R=1.5 shows that the catalyst hasT₅₀s for CO and HC decrease to 316° C. and 464° C., respectively. The NOlight-off at R=1.5 shows a T₅₀ of 375° C.

EXAMPLE 9 Light-Off Test for Type I Zeolite Catalyst

FIG. 30 shows the light-off test results for an example of Type IZeolite catalyst. A light-off test was performed on a fresh catalyst ofthe present invention. The test was performed by increasing thetemperature from about 100° C. to 640° C. at R-value=1.05. The light-offtest measures the conversions of nitrogen oxide, carbon monoxide, andhydrocarbons as a function of the catalyst system temperature. For aspecific temperature, a higher conversion signifies a more efficientcatalyst. Conversely, for a specific conversion, a lower temperaturesignifies a more efficient catalyst.

FIG. 30 shows the results for Type I catalyst with a composition of 5%Ga+8% Cu/(ZSM-5). The light-off test at R=1.05 shows that the catalysthas T₅₀s for CO at 376° C., for HC at 319° C., and for NO at 343° C.

EXAMPLE 10 Light-Off Test for Architecture Type 3, Which Comprises aSubstrate, a Washcoat, and an Overcoat, Wherein the Overcoat Comprisesat Least One Catalyst, but the Washcoat Does Not

FIG. 31 shows the light-off test results for an example of ArchitectureType 3 Catalyst, which comprises a substrate, a washcoat, and anovercoat, wherein the overcoat comprises at least one catalyst, but thewashcoat does not (washcoat comprisesLa—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂; 60:40; 100 g/L andovercoat comprises 12% Cu on Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂; 150g/L). A light-off test was performed on aged (800° C. for 16 hours,composed of a 56 second rich segment and a 4 second lean segment)catalysts of the present invention. The test was performed by increasingthe temperature from about 100° C. to 640° C. at R-value=1.05 andR-value=1.5. The light-off test measures the conversions of nitrogenoxide, carbon monoxide, and hydrocarbons as a function of the catalystsystem temperature. For a specific temperature, a higher conversionsignifies a more efficient catalyst. Conversely, for a specificconversion, a lower temperature signifies a more efficient catalyst.

The light-off test at R=1.05 shows that the catalyst has T₅₀ for CO at314° C. and a T₅₀ for HC at 464° C. The maximum NO conversion is about6% at 640° C. Increasing the R-value to 1.5 improves the NO conversion,but the HC performance deteriorates. The light-off test at R=1.5 showsthat the catalyst has T₅₀s for CO and HC decrease to 316° C. and 566°C., respectively. The NO light-off at R=1.5 shows a T₅₀ of 453° C.

EXAMPLE 11 Light-Off Test for Catalyst Systems ZPGM-1 Through ZPGM-6(Fresh and Aged)

FIGS. 32-37 show the light-off test results for ZPGM-1 through ZPGM-6. Alight-off test was performed on fresh and aged (1050° C. for 10 hrscycling between a 56 second stoichiometric (A/F=14.6) segment and a 4second lean (A/F=28.0) segment) catalysts of the present invention. Thetest was performed by increasing the temperature from about 100° C. to640° C. at R-value=1.05. The plotted temperatures in the figures weremeasured at the middle of the catalyst. The light-off test measures theconversions of nitrogen oxide, carbon monoxide, and hydrocarbons as afunction of the catalyst system temperature. For a specific temperature,a higher conversion signifies a more efficient catalyst. Conversely, fora specific conversion, a lower temperature signifies a more efficientcatalyst.

FIG. 32 shows the light-off results at R=1.05 for fresh and aged ZPGM-1catalyst system (Ce_(0.6)La_(0.4)Mn_(0.6)Cu_(0.4)O₃). The light-off testfor the fresh catalyst system shows that the CO and HC exhibit T₅₀s at288° C. and at 503° C., respectively. The maximum NO conversion is about19% at 600° C. After aging, the catalyst performance decreases for CO,HC and NO. The aged catalyst shows a T₅₀ for CO at about 600° C. Themaximum conversions for HC and NO are 19% and 2%, respectively, at 600°C.

FIG. 33 shows the light-off results at R=1.05 for fresh and aged ZPGM-2catalyst system (8% Cu impregnated onAl₂O₃+Ce_(0.64)Zr_(0.21)La_(0.15)O₂ (60:40 weight ratio of Al₂O₃ toCe_(0.64)Zr_(0.31)La_(0.15)O₂)). The light-off test for the freshcatalyst system shows that the CO and HC exhibit T₅₀s at 205° C. and at389° C., respectively. The maximum NO conversion is about 22% at 600° C.After aging, the catalyst performance decreases for CO, HC and NO. Themaximum conversions for CO, HC and NO are about 27%, 24% and 3%,respectively, at 600° C.

FIG. 34 shows the light-off results at R=1.05 for fresh and aged ZPGM-3catalyst system (8% Cu+6.1% Ce+2.4% Zr+1.5% La impregnated on 15%Sn—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (60:40 weight ratio ofSn—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂)). The light-off testfor the fresh catalyst system shows that the CO, HC and NO exhibit T₅₀sat 205° C., at 389° C., and 651° C., respectively. After aging, thecatalyst performance decreases for CO, HC and NO. The aged catalystshows a T₅₀ for CO and HC at about 599° C. and 651° C., respectively.The maximum conversion for NO is about 5% at 700° C.

FIG. 35 shows the light-off results at R=1.05 for fresh and aged ZPGM-4catalyst system (overcoat containing 12% Cu impregnated onCe_(0.64)Zr_(0.21)La_(0.15)O₂+Al₂O₃ (60:40 weight ratio ofCe_(0.64)Zr_(0.21)La_(0.15)O₂ to Al₂O₃) and a washcoat containing 8%Cu+6.1% Ce+2.4% Zr+1.5% La impregnated impregnated on 15%Sn—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (60:40 weight ratio ofSn—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂). The light-off testfor the fresh catalyst system shows that the CO, HC and NO exhibit T₅₀sat 254° C., at 442° C., and 636° C., respectively. After aging, thecatalyst performance decreases for CO, HC and NO. The aged catalystshows a T₅₀ for CO and HC at about 462° C. and 604° C., respectively.The maximum conversion for NO is about 30% at 770° C.

FIG. 36 shows the light-off results at R=1.05 for fresh and aged ZPGM-5catalyst system (overcoat containing 12.4% CuO impregnated onLa—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (25:75 weight ratio ofL—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂) and a washcoatcontaining 8% Cu+6.1% Ce+2.4% Zr+1.5% La impregnated onLa—Al₂O₃+Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂ (60:40 weight ratio ofLa—Al₂O₃ to Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂)). The light-off testfor the fresh catalyst system shows that the CO, HC and NO exhibit T₅₀sat 262° C., at 449° C., and 608° C., respectively. After aging, thecatalyst performance decreases for CO, HC and NO. The aged catalystshows a T₅₀ for CO and HC at about 571° C. and 654° C., respectively.The maximum conversion for NO is about 1% at 700° C.

FIG. 37 shows the light-off results at R=1.05 for fresh and aged ZPGM-6catalyst system (overcoat containing 10% Cu+12% Ce impregnated onMgAl₂O₄+16% Cu impregnated on Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂(60:40 weight ratio of Ce impregnated on MgAl₂O₄ to 16% Cu impregnatedon Ce_(0.6)Zr_(0.3)Nd_(0.05)Pr_(0.05)O₂) (65 g/L) and a washcoatcontaining 4% Cu+6.1% Ce+2.4% Zr+1.5% La impregnated onMgAl₂O₄+Ce_(0.64)Zr_(0.21)La_(0.15)O₂ (60:40 weight ratio of MgAl₂O₄ toCe_(0.64)Zr_(0.21)La_(0.5)O₂)). off test for the fresh catalyst systemshows that the CO, HC and NO exhibit T₅₀s at 262° C., at 463° C., and622° C., respectively. After aging, the catalyst performance decreasesfor CO, HC and NO. The aged catalyst shows a T₅₀ for CO and HC at about425° C. and 613° C., respectively. The maximum conversion for NO isabout 23% at 730° C.

EXAMPLE 12 Sweep Test for Catalyst Systems ZPGM-1 Through ZPGM-6

FIGS. 39-44 show the sweep test results for catalyst systems ZPGM-1through ZPGM-6, respectively. The sweep test was performed with an inlettemperature of 600° C., an air/fuel ratio span of ±0.2 and a cyclefrequency of 1 Hz. A sweep test indicates the catalyst performance atvarious R-values. High conversions over a large range of R-values aredesirable because that shows the catalyst can perform well under rich(R-values >1) and lean (R-values <1) engine conditions. The agedcatalyst systems were aged at 1050° C. for 10 hrs cycling between a 56second rich segment and a 4 second lean segment.

FIG. 39 shows the sweep test results for the fresh and aged ZPGM-1catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >1.05, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with R-value >0.85. The NO conversion is about 32% at R=1.0,improves to about 58% at R=1.03 and reaches 100% conversion at R=2.0.The catalytic properties for CO, hydrocarbons and NO conversion decreaseafter aging; the NO conversion is <5% over the entire R-value rangetested. The CO conversion of the aged ZPGM-1 decreases with increasingR-value. The HC conversion for the aged ZPGM-1 is best for R-valuesbetween 0.95 and 1.05.

FIG. 40 shows the sweep test results for the fresh and aged ZPGM-2catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >1.05, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with R-value >0.85. The NO conversion is about 32% at R=1.0,but improves to about 42% at R=1.03. The catalytic properties for CO,hydrocarbons and NO decrease after aging. The CO and HC conversions ofthe aged ZPGM-2 decrease with increasing R-value. The NO conversion isthe highest at R 0.85, for the aged ZPGM-2 catalyst system.

FIG. 41 shows the sweep test results for the fresh and aged ZPGM-3catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >1.05, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The NO conversion is about 60% atR=1.0, improves to about 76% at R=1.03 and reaches 100% conversion atR=1.2. The catalytic properties for CO, hydrocarbons and NO decreaseafter aging. The CO and HC conversions of the aged ZPGM-3 decrease withincreasing R-value. The NO conversion for the aged ZPGM-3 increases withR-values >0.95. The aged ZPGM-3 reaches a maximum NO conversion of about26% at R=2.0.

FIG. 42 shows the sweep test results for the fresh and aged ZPGM-4catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >0.975, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The NO conversion is about 89% atR=1.0, improves to about 92% at R=1.03 and reaches 100% conversion atR=2.0. The catalytic properties for CO, hydrocarbons and NO decreaseafter aging. The CO and HC conversions of the aged ZPGM-4 decrease withincreasing R-value. The NO conversion for the aged ZPGM-4 increases withR-values >0.95. The aged ZPGM-4 shows an NO conversion of about 16% atR=1.0, improves to about 24% at R=1.03 and reaches 89% conversion atR=2.0.

FIG. 43 shows the sweep test results for the fresh and aged ZPGM-5catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >0.975, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The NO conversion is about 83% atR=1.0, improves to about 90% at R=1.03 and reaches 99% conversion atR=2.0. The catalytic properties for CO, hydrocarbons and NO conversiondecrease after aging. The CO and HC conversions of the aged ZPGM-5decrease with increasing R-value. The NO conversion for the aged ZPGM-5increases with R-values >1.05. The aged ZPGM-5 exhibited no NOconversion at R=1.0, 9% at R=1.03 and reaches 54% conversion at R=2.0.

FIG. 44 shows the sweep test results for the fresh and aged ZPGM-6catalyst system. The sweep results for the fresh catalyst show that theCO conversion decreases with R-values >0.975, while the hydrocarbon (HC)conversion decreases with increasing R-values. The NO conversionincreases with increasing R-values. The NO conversion is about 91% atR=1.0, improves to about 97% at R=1.03 and is >99% conversion at R=1.05.The catalytic properties for CO, hydrocarbons and NO conversion decreaseafter aging. The CO and HC conversions of the aged ZPGM-6 decrease withincreasing R-value. The NO conversion for the aged ZPGM-6 increases withR-values >0.975. The aged ZPGM-6 exhibited an NO conversion of about 17%at R=1.0, 31% at R=1.03 and reaches 98% conversion at R=2.0.

EXAMPLE 13 Sweep Test for Type G Transition Metal Catalysts

FIG. 45 shows the sweep test results for examples of Type G catalysts.The sweep test was performed with an inlet temperature of 600° C., anair/fuel span of ±0.2 and a cycle frequency of 1 Hz. A sweep testindicates the catalyst performance at various R-values. High conversionsover a large range of R-values indicate a promising catalyst because itcan perform well under rich (R-values >1) and lean (R-values <1) engineconditions. The aged catalyst systems were aged at 1050° C. for 10 hrscycling between a 56 second rich segment and a 4 second lean segment.

FIG. 45 shows the sweep test results for the fresh and aged Type Gcatalyst comprising 10% Cu/CuLa_(0.04)Al_(1.96)O₄. The sweep results forthe fresh catalyst show that the CO conversion decreases withR-values >1.0, while the hydrocarbon (HC) conversion decreases withincreasing R-values. The NO conversion increases with increasingR-values. The NO conversion is about 90% at R=1.0, improves to about 94%at R=1.03 and is 98% conversion at R=1.2. The catalytic properties forCO, hydrocarbons and NO decrease after aging. The CO and HC conversionsof the aged decrease with increasing R-value. There was not any measuredNO conversion for the aged catalyst.

EXAMPLE 14 Sweep Test for Type D Transition Metal Catalysts

FIG. 46-48 shows the sweep test results for examples of Type Dcatalysts. The sweep test was performed with an inlet temperature of450° C., an air/fuel span of ±0.2 and a cycle frequency of 1 Hz. A sweeptest indicates the catalyst performance at various R-values. Highconversions over a large range of R-values indicate a promising catalystbecause it can perform well under rich (R-values >1) and lean (R-values<1) engine conditions. The aged catalyst systems were aged at 800° C.for 16 hrs cycling between a 56 second rich segment and a 4 second leansegment.

FIG. 46 shows the sweep test results for the fresh and aged Type Dcatalyst comprising 12.4%CuO/Ce_(0.3)Zr_(0.6)Nd_(0.05)Pr_(0.05)O₂+Al₂O₃, 75:25. The sweep resultsfor the fresh catalyst show that the CO conversion decreases withR-values >1.05, while the hydrocarbon (HC) conversion decreases withincreasing R-values. The NO conversion increases with increasingR-values above 1.15. The NO conversion is about 6% at R=1.15, andimproves to about 42% at R=1.5.

FIG. 47 shows the sweep test results for the fresh and aged Type Dcatalyst comprising 16% CuO/Ce_(0.3)Zr_(0.6)Nd_(0.05)Pr_(0.05)O₂. Thesweep results for the fresh catalyst show that the CO conversiondecreases with R-values >1.05, while the hydrocarbon (HC) conversiondecreases with increasing R-values. The NO conversion increases withincreasing R-values. The NO conversion is about 7% at R=1.05, andimproves to about 38% at R=1.5.

FIG. 48 shows the sweep test results for the fresh and aged Type Dcatalyst comprising 10% Cu+12% Ce/La—Al₂O₃. The sweep results for thefresh catalyst show that the CO conversion decreases withR-values >1.05, while the hydrocarbon (HC) conversion decreases withincreasing R-values. The NO conversion increases with increasingR-values above 1.05. The NO conversion is about 3% at R=1.05, andimproves to about 59% at R=1.5.

EXAMPLE 15 Sweep Test for Type G Transition Metal Catalysts

FIG. 49 shows the sweep test results for examples of Type G catalysts.The sweep test was performed with an inlet temperature of 450° C., anair/fuel span of ±0.2 and a cycle frequency of 1 Hz. A sweep testindicates the catalyst performance at various R-values (moles ofreductant divided by moles of oxidant). High conversions over a largerange of R-values indicate a promising catalyst because it can performwell under rich (R-values >1) and lean (R-values <1) engine conditions.The aged catalyst systems were aged at 800° C. for 16 hrs cyclingbetween a 56 second rich segment and a 4 second lean segment.

FIG. 49 shows the sweep test results for the fresh and aged Type Dcatalyst comprising 20% CuO/MgLa_(0.04)Al_(1.96)O₄. The sweep resultsfor the fresh catalyst show that the hydrocarbon (HC) conversiondecreases with increasing R-values. The NO conversion increases withincreasing R-values. The NO conversion is about 9% at R=1.05, andimproves to about 88% at R=1.5.

Although the present invention has been described in terms of specificembodiments, changes and modifications can be made without departingfrom the scope of the invention which is intended to be defined only bythe scope of the claims. All references cited herein are herebyincorporated by reference in their entirety, including any referencescited therein.

1-146. (canceled)
 147. A method for reducing nitrogen oxide emission,comprising: exposing an exhaust to a catalyst, wherein the exhaust hasan R value of greater than 1.0, and wherein the catalyst issubstantially free of platinum group metals.
 148. The method of claim147, wherein the catalyst is one or more selected from the groupconsisting of a ZPGM transition metal catalyst, a zeolite catalyst, anda mixed metal oxide catalyst.
 149. The method of claim 147, wherein thecatalyst is completely free of platinum group metals.
 150. The method ofclaim 147, wherein the exhaust is one or more selected from the groupconsisting of an engine, a boiler, a utility plant, a processing plant,and a manufacturing plant.
 151. A method for improving carbon monoxideand hydrocarbon reduction in an exhaust comprising: exposing the exhaustto a first catalyst system, exposing a portion of the exhaust to asecond catalyst system, wherein the first catalyst system and the secondcatalyst system are in series; and introducing air into the portion ofthe exhaust before the exposing to the second catalyst system, whereinthe first catalyst system comprises a first catalyst and issubstantially free of platinum group metals, wherein the air comprisesoxygen, wherein the second catalyst system comprises a second catalystand is substantially free of platinum group metals; and wherein theportion of the exhaust results in an air to fuel ratio above about 14.7.152. The method of claim 151, wherein the portion of the exhaust is 100%of the exhaust.
 153. The method of claim 151, wherein the introducingcomprises injecting.
 154. The method of claim 151, wherein the firstcatalyst is one or more selected from the group consisting of a ZPGMtransition metal catalyst, a zeolite catalyst, and a mixed metal oxidecatalyst.
 155. The method of claim 151, wherein the second catalyst isone or more selected from the group consisting of a ZPGM transitionmetal catalyst, a zeolite catalyst, and a mixed metal oxide catalyst.156. The method of claim 151, wherein the first catalyst system iscompletely free of platinum group metals.
 157. The method of claim 151,wherein the second catalyst system is completely free of platinum groupmetals.
 158. The method of claim 151, wherein the second catalyst systemcomprises at least one platinum group metal.
 159. The method of claim151, wherein the air consists of oxygen.
 160. The method of claim 151,wherein the exhaust is one or more selected from the group consisting ofan engine, boiler, utility plant, processing plant, and manufacturingplant.
 161. The method of claims 151, further comprising: adding asecond exhaust to the portion after the first catalyst system and beforethe introducing.
 162. The method of claim 151, further comprising:adding a second exhaust to the portion after the first catalyst systemand after the introducing.
 163. The method of claim 151, wherein theexhaust comprises a portion and a bypass.
 164. The method of claim 151,further comprising: diverting the bypass from the exposing to the secondcatalyst system.
 165. A method for improving the reduction ofhydrocarbon, carbon monoxide, and nitrogen oxide in an exhaustcomprising: exposing the exhaust to a first catalyst system, wherein theexhaust has an R value of greater than 1.0, and wherein the firstcatalyst system comprises a first catalyst and is substantially free ofplatinum group metals; and exposing a portion of the exhaust to a secondcatalyst system, wherein the second catalyst system comprises a secondcatalyst and is substantially free of platinum group metals, wherein thefirst catalyst system and the second catalyst system are in series; andintroducing air into the portion of the exhaust after the first catalystsystem, wherein the air comprises oxygen, and wherein the portion of theexhaust has an air to fuel ratio above about 14.7 before the exposing tothe second catalyst system.
 166. The method of claim 165, wherein thefirst catalyst is selected from the group consisting of a ZPGMtransition metal catalyst, a zeolite catalyst, and a mixed metal oxidecatalyst.
 167. The method of claim 165, wherein second catalyst isselected from the group consisting of a ZPGM transition metal catalyst,a zeolite catalyst, and a mixed metal oxide catalyst.
 168. The method ofclaim 165, wherein the first catalyst is completely free of platinumgroup metals.
 169. The method of claim 165, wherein the second catalystis completely free of platinum group metals.
 170. The method of claim165, wherein the air consists of oxygen.